The present invention relates to a disconnectable electromagnetic jack or eccentric actuator for controlling a mobile member for automatically adjusting a machine.
Among the numerous applications possible, the one for which technical problems are at the origin of the invention belongs to the domain of heat engines, and particularly for the automobile vehicle where it has been observed that the regulation of the temperature of the intake air had a considerable direct influence on fuel saving.
According to usual practice, this regulation is obtained due to the controlled mix of a variable quantity of fresh ambient air sucked in from outside the operational enclosure of the engine and of reheated air, for example air in contact with the exhaust pipe.
Optimum metering of the air mixture admitted into the engine is generally obtained by the displacement of a mobile flap located upstream of the air filter and at the junction of two admission conduits. The flap is usually actuated by the deformation of a membrane subjected to the depression of the inlet manifold via a valve of which the leakage rate is regulated by a device incorporating a bimetallic strip sensitive to the variations in temperature of the air admitted.
The major drawback of this technique, although simple and economical to carry out, is the imprecise control that it achieves, by reason of the inherent elasticity of the device, due to the use of a membrane. In fact, under the effect of the rhythmic pulsations of the engine, the associated mass of the mobile elements of the device is constantly subjected to more or less resonant oscillations detrimental to the desired precision of control.
It is essentially an object of the present invention to eliminate this drawback by proposing a simple, reliable device, economical to produce, whose positive action is virtually bereft of natural elasticity, prevents the tendency to parasitic vibrations and consequently procures strict precision of adjustment in a predetermined range.
The device of the invention further aims at instantaneous disconnection of the positive control action simply by switching off its electrical supply, by design or by accident.